1. Field of the Invention
This invention relates to a protection control measurement system which performs protection, control and measurement of an electric power system, and relates to a system with excellent economy and maintainability, which collects protection control measurement data using a communication network.
2. Description of the Related Art
Data communication means between terminals, installed in transformer substations, electric power plants, and similar of the prior art, have generally employed Ethernet (a registered trademark) and TCP/IP general-use protocols. In particular, as means for transmitting data reliably in a fixed length of time using Ethernet, communication means such as those described in Japanese Patent Application Laid-open No. 2005-124206 and Japanese Patent Application Laid-open No. 2000-92109 have been proposed.
In Japanese Patent Laid-open Application No. 2005-124206, a method of transmission of real-time data over Ethernet is disclosed in which, in order to resolve the problem of the occurrence of fluctuations in the delay times of transmission packets by suppressing collisions which occur when large amounts of real-time data are transmitted simultaneously, priority rights are assigned to real-time data, and in addition a communication protocol is adopted for collision avoidance. In this Japanese Patent Application Laid-open No. 2005-124206, the transmitted real-time data is video data.
Further, in Japanese Patent Application Laid-open No. 2000-92109 a duplex Ethernet hub device and network for realizing real-time data transmission are disclosed, for cases in which scheduled data must be reliably transmitted over an industrial network within a fixed time. Specifically, in a network adopting full-duplex Ethernet, a configuration is disclosed in which are provided transmission monitoring means for monitoring the amount of transmission data from each station device in each period, and transmission control means for imparting instructions to station devices for transmission control, based on data amounts acquired via the transmission monitoring means. By this means, control data for industrial use and similar for which real-time transmission is necessary can be transmitted with a guarantee of transmission within a fixed time.
There is a desire to apply communication means using Ethernet such as those described above when performing protection, control and measurement of power systems and power installations. Use of Ethernet in this way is advantageous with respect to economy and maintainability; for example, electric quantities can be collected from an electric power system or power installations at a plurality of locations via such Ethernet, protection control measurement operations can be performed to judge whether protection and control of the electric power system is necessary, and electric quantities at a plurality of locations can be compared and measured, among other advantages.
As explained above, in protection control measurement operations of power systems and similar, when transmitting electric quantities over a communication network using Ethernet, it is necessary to introduce communication technologies such as those disclosed in Japanese Patent Application Laid-open No. 2005-124206 and Japanese Patent Application Laid-open No. 2000-92109 when performing real-time transmission.
However, in a protection control measurement system which performs protection, control and measurement of an electric power system, among the data used in protection control measurement, the collected voltage, current, and other electric quantity data must be transmitted in real-time, with arrival times at terminals and parent stations guaranteed; but the set points of protection relays, values of various settings and similar are non-real-time data, for which guarantees of arrival times are more relaxed, and so need not be transmitted in real-time. Hence while Japanese Patent Application Laid-open No. 2005-124206 and Japanese Patent Application Laid-open No. 2000-92109 present means for realizing real-time transmission, there is no disclosure relating to protection control measurement data which includes non-real-time data for use in protection control measurement systems.
Specifically, in Japanese Patent Application Laid-open No. 2005-124206, communication means are proposed in which priority rights are assigned to real-time data, and in addition a communication protocol is applied for collision avoidance; but as explained above, the real-time data which is transmitted and received is video data, and is not protection, control, or measurement data. And, in Japanese Patent Application Laid-open No. 2000-92109, the data transmitted and received in real-time transmission within an industrial network is industrial data, the details of which are unclear.
That is, as described above, in Japanese Patent Application Laid-open No. 2005-124206 and Japanese Patent Application Laid-open No. 2000-92109 it is assumed that all data is data which must be transmitted in real-time. Hence when the technology of Japanese Patent Application Laid-open No. 2005-124206 or the technology of Japanese Patent Application Laid-open No. 2000-92109 is applied to a protection control measurement system, it may be possible to transmit electric quantity data and similar in real-time, but various setting values and other non-real-time data is also transmitted by real-time communication means, so that there is the cost-related problem that the hardware scale must be made larger than is necessary.